This invention relates to a fuel injection nozzle for an internal combustion engine, such as a diesel engine. More particularly, it relates to a fuel injection nozzle including a hollow nozzle body and a valve member liftably disposed in the nozzle body to selectively block communication between a fuel passage and the internal openings of injection orifices in the nozzle body.
Some conventional fuel injection nozzles for diesel engines include hollow nozzle bodies and valve members liftably disposed in the nozzle bodies to selectively close the internal openings of injection orifices in the nozzle bodies. In such a fuel injection nozzle, the effective cross-sectional area of the fuel supply path including the injection orifices abruptly increases to its maximum as the valve member lifts. Therefore, during the initial stage of fuel injection, a relatively great amount of fuel is injected into a combustion chamber of the engine. However, it is desirable to reduce somewhat the amount of fuel injected during this stage from the standpoint of reducing combustion shocks, vibrations or sounds, and of reducing engine emissions of harmful NOx (oxides of nitrogen).